The Neroverdi enjoyed their best ever top-flight campaign during 2015-16, eventually finishing in sixth position and qualifying for the Europa League.
Things have not quite gone to plan this season however, with Eusebio Di Francesco's side currently languishing in 16th position in the Serie A standings, while their 3-2 defeat at Athletic Bilbao on Thursday means they can no longer qualify from their Europa League group.
Sassuolo have failed to win any of their last eight matches in all competitions and Squinzi concedes his side have fallen short of his expectations so far this term.
“We have not achieved the results we were expecting,” confessed Squinzi on Radio CRC.
“The season is still long and I am sure we’ll get back on track. Unfortunately we lost the Europa League by allowing Rapid Vienna to score two late goals at the Mapei Stadium. In Serie A too we are paying the price for conceding in the final minutes."
Squinzi believes the club's European campaign has had a detrimental effect on their league form, and he hopes the team’s Serie A fortunes can now improve following their continental exit.
He added: “(Napoli President Aurelio) De Laurentiis was right when he said the Europa League is a competition that saps your energy and is thus damaging for Serie A form.”